The present invention relates to a multi-nozzle ink jet head for applying pressure to pressure chambers and ejecting ink drops from nozzles and a manufacturing method thereof, and in particular to a multi-nozzle ink jet head for which the leading out of electrodes from a row of pressure energy generators is improved and a manufacturing method thereof.
An ink jet recording head has nozzles, ink chambers, an ink supply system, an ink tank, and transducers; by generating pressure in the ink chambers using the transducers, ink particles are ejected from the nozzles, and characters or images are recorded on a recording medium such as paper.
For example, in well-known forms, the transducer is used a heat-generating element, or else a thin-plate-shaped piezoelectric element having the whole of one surface thereof bonded to the outer walls of an ink chamber. In the case that a piezoelectric element is used, a pulse-like voltage is applied to the piezoelectric element, thus bending the composite plate comprising the piezoelectric element and the outer walls of the ink chamber, and the displacement/pressure generated through the bending is transmitted to the inside of the ink chamber via the outer walls of the ink chamber.
A sectioned perspective view of a conventional multi-nozzle ink jet head 100 using piezoelectric elements is shown in FIG. 20. As shown in FIG. 20, the head 100 is constituted from a row of piezoelectric bodies 111, individual electrodes 112 formed on the piezoelectric bodies, a nozzle plate 114 in which are provided nozzles 113, ink chamber walls 117 made of a metal or a resin that, along with the nozzle plate 114, form ink chambers 115 corresponding respectively to the nozzles 113, and a diaphragm 116.
A nozzle 113 and a piezoelectric body 111 are provided for each ink chamber 115, and the periphery of each ink chamber 115 and the periphery of the corresponding diaphragm 116 are connected together strongly. A piezoelectric body 111 for which a voltage has been applied to the individual electrode 112 deforms the corresponding part of the diaphragm 116 as shown by the dashed lines in the drawing. As a result, an ink drop is ejected from the nozzle 113.
Application of voltages to each of the piezoelectric bodies 111 is carried out separately using electrical signals from a printing apparatus main body via printed circuit boards. FIG. 21 is a drawing showing the constitution of connections between the conventional head and the printed circuit boards. In the example of FIG. 21, the head 100 has 8 rows and 8 columns of nozzles 113, i.e. of piezoelectric bodies 111 and individual electrodes 112. Corresponding to this, flexible printed circuit boards 110 are provided for connecting the driver circuitry of the apparatus to the individual electrodes 112.
In this prior art, the individual electrodes 112 are connected to the terminals of the printed circuit boards 110 by wires 120 through wire bonding. Moreover, art in which an FPC wiring board is connected directly is also known.
Moving on, due to demands to increase printing resolution, there are demands to increase the density of the nozzle arrangement on heads. If the nozzle density is raised, then the contact spacing between terminals (internal electrodes) is reduced. For example, the nozzle density of a head using piezoelectric bodies is currently about 150 dpi, but is advancing to 180 to 300 dpi, and further to 360 dpi, and hence the contact spacing is becoming lower.
However, currently the best contact spacing with wire bonding using semiconductor manufacturing is 150 dpi, with 300 dpi contacts being developed in the case of FPC connection. If electrical connection is carried out by providing contacts on top of or near to the piezoelectric bodies 111 as conventionally, then a problem of joining of neighboring contacts (shorting) may arise. Moreover, when connecting a large number of points in a short time, the load on the piezoelectric bodies 111 becomes very high, and with thin-film piezoelectric bodies there is a risk of breakage, and hence connection is extremely problematic.
Moreover, wire bonding requires about 1 second per point, and hence if the number of points rises due to increasing the density, then the manufacturing time increases, leading to an increase in cost. For example, with the example of FIG. 19, there are 48 points, and hence 48 seconds would be required. Furthermore, even in the case of FPC connection, it is necessary to connect the FPC to a printed circuit board having the driving circuitry thereon, and hence it is difficult to reduce the cost.
It is an object of the present invention to provide a multi-nozzle inkjet head, for which connection to driving circuitry can be carried out easily even though the nozzles are arranged at a high density, and a manufacturing method thereof.
Moreover, it is another object of the present invention to provide a multi-nozzle ink jet head, for which connection to the driving circuitry is possible even though connection work is not carried out at the head part, and a manufacturing method thereof.
Furthermore, it is yet another object of the present invention to provide a multi-nozzle ink jet head, for which damage to the head can be prevented and moreover the cost can be reduced, and a manufacturing method thereof.
To attain these objects, a form of the multi-nozzle ink jet head of the present invention has a nozzle plate in which are formed a plurality of nozzles, an ink chamber forming member in which are formed a plurality of ink chambers communicating with the nozzles, energy generating parts that apply energy to the ink chambers for ejecting ink from the nozzles, and wiring patterns that are provided on the ink chamber forming member and are for applying driving signals to the energy generating parts.
A method of manufacturing a multi-nozzle ink jet head of the present invention has a step of forming energy generating parts that apply energy to ink chambers for ejecting ink from nozzles, a step of providing, on the energy generating parts, an ink chamber forming member having wiring patterns for applying driving signals to the energy generating parts, a step of forming, in the ink chamber forming member, a plurality of ink chambers communicating with the nozzles, and a step of providing, on the ink chamber forming member, a nozzle plate in which are formed the plurality of nozzles.
With the present invention, by providing wiring patterns on the ink chamber forming member, the ink chamber forming member is also used as a connecting cable. As a result, it becomes unnecessary to carry out connection at the head part, and hence connection between the head and the driving circuitry becomes easy even though the nozzle density is high, damage to the head can be prevented, and the cost of the head can be reduced.
Moreover, in a PCT application (PCT/JP/99/06960) filed on 10 Dec. 1999, the present inventors proposed a head in which piezoelectric body layers are provided even in regions other than the regions of the pressure chambers, and wiring parts from individual electrodes are provided on the piezoelectric body layers, and hence connection to the outside of the head can be carried out at a position away from the row of the piezoelectric bodies of the pressure chambers.
However, even in that proposal, a connecting cable is necessary for connecting to the external circuitry.
With the present invention, such a connecting cable is not necessary, and hence the connection to the external circuitry is simplified.
Moreover, in the multi-nozzle ink jet head of the present invention, the energy generating parts have a common electrode, energy generating layers that are provided on the common electrode in correspondence with the ink chambers, and individual electrode parts that are provided on the generating layers in correspondence with the ink chambers, and the wiring patterns have wiring patterns for the individual electrode parts, and a wiring pattern for the common electrode. As a result, even with a high nozzle density, a large number of nozzles can be driven easily from external circuitry, and connection to the external circuitry becomes easy.
Moreover, with the multi-nozzle ink jet head of the present invention, by the energy generating layers being piezoelectric body layers, and the wiring patterns being embedded in the ink chamber forming member, the walls of the ink chambers can be reinforced by the wiring patterns.
Moreover, a multi-nozzle ink jet head of the present invention has electrically conductive paths that pass through at least the energy generating layers and electrically connect the individual electrodes to the wiring patterns.
With a method of manufacturing a multi-nozzle ink jet head of the present invention, the step of forming the energy generating parts has a step of providing, on a substrate, a plurality of individual electrodes, and a plurality of energy generating layers, and a step of providing a common electrode on the generating layers, and the step of forming the plurality of ink chambers has a step of forming electrically conductive members for electrically connecting the individual electrodes and the wiring patterns together.
As a result, connection to the individual electrodes can be carried out easily, even though the wiring patterns are provided on the ink chamber forming member.
Moreover, with a multi-nozzle ink jet head of the present invention, control circuitry connected to the wiring patterns is provided on the ink chamber forming member. As a result, the connection becomes yet easier, and simplification is possible.
Moreover, a multi-nozzle ink jet head of the present invention has a metal mask layer provided on the ink chamber forming member for forming the ink chambers, and an electrically conductive layer provided in the pressure chambers for electrically connecting the metal mask layer and the common electrode together.
With a method of manufacturing a multi-nozzle ink jet head of the present invention, the step of forming the plurality of ink chambers comprises a step of forming the plurality of ink chambers using a metal mask formed on the ink chamber forming member, and a step of plating electrically conductive members on the ink chamber forming member, thus forming the above-mentioned electrically conductive members, and at the same time forming, in the ink chambers, an electrically conductive layer that electrically connects the metal mask and the common electrode together.
As a result, the ink chambers can be formed accurately using the metal mask, and moreover the strength of the ink chambers can be increased. Furthermore, through the electrically conductive layer, the common electrode can be connected to the wiring pattern using the metal mask.
Other objects and forms of the present invention will become apparent from the following description of embodiments of the invention and the drawings.